Catalytic polymerization of olefinic hydrocarbons



Dec. 14', 1948. J. J. STADTHERR CATALYTIC POLYMERIZATIN OF OLEFINIC HYDROCARBONS 2 Sheets-Sheet 1 Filed MarCh 26, 1945 INVENToR. John' James Sadhez-r ATz'oRAmY.

J. J. STADTHERR 2,456,338

` CATALYTIC POLYMERIZATION OF OLEFINIC HYDROCARBONS V Filed March 26, 1945 Dec. 14, 1948.

2 Sheets-Sheet 2 atentec ec. i4, i943 CATALYTIC POLYMERIZATION OF OLEFINIC HYDROCARBONS John J. Stadtherr, Newark, Ohio, assignor to The Pure Oil Company, Chicago, lil., a corporation of Ohio Application March 26, 1945, serial No. 584,979

Y This invention relates to the selective catalytic polymerization of olenic hydrocarbons to hydrocarbons boiling within the gasoline boiling range.

Methods are Well known for selectively polymerizing C4 oleiins by passing such olefins over a solid polymerizing catalyst such as kieselguhr impregnated with phosphoric acid, and dried. The polymer obtained in this process after hydrogenation is a high grade aviation blending stock.

I have discovered that if stabilizer gases separated from cracked gasoline are separated into C3 and lighter, C4 and C5 fractions, the C3 and lighter and C fractions can be recombined and polymeriz'ed separately from the C4 fraction to give a polymer, which upon hydrogenation results in a high grade aviation gasoline, and that the reaction product from the polymerization of the combined C3 and Csiractions can be used to heat the C4 fraction sufficiently to selectively polymerize it without the necessity of supplying additional heat thereto.

An object of the invention is to provide an improved method for polymerizing mixed oleiinic gases.

Another object of the invention is to provide a selective method for polymerized mixed olens in order to obtain increased yields of aviation gasoline.

Still another object of the invention is to provide a selective method for polymerizing olefin hydrocarbons in which the heatfcontent of the reaction product from one stagev is used to heat .the charging stock ina separate polymerization stage. f

Other objects of the invention will become manifest from the following description and accompanying drawings in which Figure 1 is a flow 'sheet showing apparatus suitable for carrying out the invention; and Figure 2 is a flow sheet of apparatus for carrying out a modication of the invention. Y

It should be understood that in both Figures 1 and 2 auxiliary equipment, such as pumps, compressors, valves and coolers, have been omitted.

Referring to Figure 1, numeral I indicates a feed line through which liquefied gas containing C2, C3, C4 and C5 olefins, as well as C3, C4 and C5 and lower molecular weight parafns, is charged to an accumulator 3. The gas charged through feed 'line I may be stabilizer gas from an oil cracking operation, either thermal, catalytic or a combination thereof. Cracked stabilizer gas may have the following approximate analysis:

CH4 6.0 C2 hydrocarbons 19.2 C3 hydrocarbons 34.2 C4 hydrocarbons 35.6 C5 hydrocarbons 1 5.0

It Will be understood, however, that the analysis will Vary with the type of operation in which the gas is produced. From the accumulator 3 the liqueed gas is charged through line 5 to a caustic wash tower 'l in order to remove hydrogen suliide and any low boiling mercaptans which may be contained therein. lAn aqueous sodium 'hydroxide solution containing from 15 to 20% of sodium hydroxide is suitable for use in the wash tower. Contact between the liqueed gas and caustic soda solution may be countercurrent, with cyclic circulationof the caustic soda solution, and the caustic washed gas may be Water washed and settled in a suitable settler not shown. The washed liqueed gas leaves the top of the tower 'I through line 9 and is charged into the intermediate zone of a debutanizer IIl under a pressure of approximately 300 to 450 pounds per square inch. In tower I I C2, C3 and C4 hydrocarbons are vaporized and leave the top of the tower through line I3. The remaining'liquid portion of the charging gas which now is composed chiefly of C5 hydrocarbons leaves the bottom of the debutanizer through line I5 at a temperature of approximately 330 F. The mixture of gases passing through line I3 and composed chiefly of C2, C3 and C4 hydrocarbons enters intermediate portion of depropanizer I 'I which is also maintained at a pressure of between approximately 300 and 450pounds per square inch. In the depropanizer 'II' C3 and lighter hydrocarbons are separated from C4 hydrocarbons, C3 and lighter hydrocarbons' being withdrawn from the top of the tower throughline I9 and the C4'hydrocarbons being Withdrawn from the bottom of depropanizer l1 through line lliti at a temperature of about 260 F.. The gases in line I9 are preferably condensed to liquid and then pumped un- `der a pressure of 300 to 1000 pounds per square 'inerzed gases. The polymer leaves the bottom 'vof thestripper through line vl@ and the gas is .fraction will pass downwardly .through catalytic i reactor 80 and the reaction products in the bottom pass through the line 82. From 'the line zthe reaction products pass into an intermediate pointv vof .stripper 84 where polymer is separated from :the unreacted gas. The polymer is withdrawn from the stripper .S4 through line 86 andthe `unreacted gas leaves the top of `stripper li through line 88 joining gases from stripper 6B. i?,

Combined gases from the strippers 68 and `li pass through condenser 'i4 to accumulator l'l. Any uncondensed gas leaves the accumulator 'I6 through line 9B. Liqueed gas is withdrawn from accumulator 7S through line 92 and may be re- H cycled through either lines 94, 96 or 98, -or may be divided in any desired proportion as required to maintain the desired temperatures in the reactors 60 and 80. The recycled gas is -preferably injected into the reactors 60 and 80 at a plurality of points along the length of the reactor in order to maintain the temperature in the reactor within the desired limit of temperature range. Recycle gas in excess of that required to keep the temperature in the reactor within the desired range is recycled to the heater.

Recycle stock may be heated, if desired, by heat interchange with gases and/or polymers leaving the strippers 68 and 84.

It will be seen that in accordance with the method of operation of Figure 2, the combined C2, Ca and C fractions on the one hand, and the C4 fraction on the other, are separately polymerized under conditions most favorable to their polymerization, and that the heat content of the C2, C3 and C5 fraction is utilized to indirectly heat the C4 fraction to the desired temperature for Iits polymerization, thereby enabling recovery of the polymers separately from each reaction stage.

By operating in accordance with the method outlined in Figure 2 a polymer boiling within the aviation gasoline boiling range can be obtained from the C2, C3 and C5 fractions plus the polymer from C4 polymerization, which upon hydrogenating and leading with 4 cc. of tetraethyl lead fluid will yield a product having a motor octane number of 99.6. An aviation gasoline fraction can be obtained from the C4 polymer only, which h-as a motor octane number of approximately 94 before adding tetraethyl lead, and over 100 motor octane with the addition of 4 cc. of tetraethyl lead.

In accordance with the method described, substantially all the olefins present in stabilizer gas can be utilized in the lmanufacture of aviation gasoline, thereby greatly increasing the yield of .aviation gasoline over that which has heretofore been produced from cracked g-ases.

In either the process represented by Figure 1 or Figure 2, the order of the depropanizer and the 7 feed debutanizer may be reversed -provided the separated fractions `are not combined differently than in the manner indicated.

It is claimed:

1. The method of converting stabilizer gases yfrom yan oil'l-crackng operation; having the following approximate composition:

omg". 5.o C2 hydrocarbons 1 19.2 C3 hydrocarbons 34.2 C4 hydrocarbons 35.6 vC5 hydrocarbons 5.0

to hydrocarbons boiling within the gasoline range comprising separating said gasesinto a fraction composed chie'yof C4 hydrocarbons and a fraction comprised .chiefly of C2Ca and C5 .hydrocarbons, subjecting the C2, C3 and C5 fraction to polymerization in the presence of .a solid phosphorus acid catalyst in a rst zone, heating the C4.frac ytion by meansofA the reaction products from the C2, C3 and C5 polymerization stage and subjecting the C4 fraction to catalytic polymerization in a second zone in the presence of a solid phosphoric acid catalyst at -a temperature lower than the temperature oi .the zone in which the C2, C3 andCs fraction is polymerized.

' 2. Method Ain accordance with claim 1 in which the C4 fraction is heated by direct contact withthe C2, Cs and C5 polymerization reaction products.

3. Method in accordance with claim 1 in which the C4 fraction is heated by indirect contact with the C2, Ca and C5 polymerization reaction products.

4. The method in accordance with claim 1 in which unreacted hydrocarbons are recycled to a third catalytic polymerization zone :and the temperature in said third zone is intermediate that of said rst and second zones.

5. Method in accordance with claim 1 in which unreacted hydrocarbons are 'recycled in part to the C2, C3 and C5 polymerization zone and -in part to the C4 -polymerization zone at a lower temper-ature than the temperature existing in the respective zone.

6.' A process for converting stabilizer gases from oil cracking operations into gasoline-boiling hydrocarbons comprising separating said gases into a C3 and lighter fraction, a C4 fraction and a C5 fraction, heating the combined C's and lighter C5 fractions and contacting the heated fractions at a temperature of approximately 400 to 450 F. under pressure in excess of 300 pounds per square inch with solid phosphoric acid catalyst, cooling the reaction products to approximately 375 to 425 F. by admixture with recycle stock and subjecting the resulting mixture to polymerization at a pressure in excess of 300 pounds per square inch in the presence of solid phosphoric acid catalyst, mixing the hot reaction products from the second polymerization stage wherein the combination of recycle, Ca rand lighter, and C5 fractions ar-e reacted with the cooler C4 fraction in order to heat the latter and subjecting the mixture to polymerization at a temperature of approximately 300 to 375 F. and pressure in excess of 300 pounds lper square inch in the presence of solid phosphoric acid catalyst, separating unreacted fractions from the resulting polymer and recycling the unreacted fractions as aforesaid.

7. A process for converting cracked stabilizer gases containing olens having up to 5 carbon atoms in the molecule comprising separating said gas into a C5 fraction, a C4 fraction and a iraction containing C3 and lighter fractions, combining the C5 and the Ca and lighter fractions, subjecting the .combined fractions to polymerization in the presence of a solid phosphoric acid polymerization catalyst, utilizing the heat content of the reaction products from the aforesaid poly-v @mefizatiomstepftoheatrme gom-faction to :ly-

merzation temperatmsxplymeri-zng :the Q4-fractlon in the presence of a. solid phosphoric acid polymerization catlys't at a 'temperature below litho temperature of 'thefu'st 'merit' nejd polymeri- Lzagtion step, separating unreactdllgydrocarbons ,t-rom the reaction products oftheupdlymerization 'steps' and utilizing said unreactedhydrooarbons fitomregulatefthe memperatu-reiinat :leasteoneiofzthe quilymrzationsimpa 'f 18. Processimaccoxfdanoetwithvfolaim Trim-which th'eCC fraction -.=is:-hea.ted1sto reaction. temperature u'rzryf'nfdrect heathexchangerwthzthe yreaction :prod- A'fmom therlrst polymerization step Iamfthe recycle stockdsf-Sinljected dlr'vectlyxntozmhe reac- =1 -ltion zonedn :Vatileast-f one; polymerization step.

fl9.'lPo`oess `in1accordamcewthLclstml7..in;,which fltherst polymerization 1 step -s= carriedout vin the Jpre'sonoe of -solid phosphoric acid scatalystotAOO" 150145021 Rand SBOOI-tolllOOOfpoun'ds .pensquare inch.,

andfthe-'seeond polymerization step :is fcarr'ied aout REFERENCES CITED The -following references are of 4recorin the file-fof this patent:

YUNlIYED STATES PATENTS 'Number fNa'm'e Date 1231171207 ,-:Boultbee `Augu29, 1939 .12,181,640 Dea-nesy Nov. '28,51939 :2,224,071 Wassermann Dec. 3,1940 23245,'733 l'Suloknw v J une1 17, 1:94:11 `230833516 Borden Jan. .19, 1943 `:2;3255891 VilandlY -Aug. 3, 194.3 '2,353,832 Kemp Ju1yv18, 1944 i2,3f24;95 Helmers Apr. 17,1945 3773111 l.frey .June.15,f:1945

Certicate of Correction PatentNo. 2,456,338 December 14, 1.948.

JOHN J. STADTHELRR It is hereby certified that erro 1` appears in the printed specification of the abovenumbered patent requiring correctlon as follows:

Column 6, line 45, claim 6, after the Word lighter insert and;

and that the said Letters Patent should be read with this correction therein that the same may conform to the record of the case in the Patent Olice.

Signed and sealed the 5th day of April, A. D. 1949.

THOMAS F. MURPHY,

Assistant Oommzssoner of Patents. 

